Estimation of ion mixture composition with CHEmically Modified Field Effect Transistors

The paper deals with the problem of ion mixture composition determination. This is realized using the CHEmically Modified Field Effect Transistor (CHEMFET), which is closely related to the conventional Metal-Oxide-Semiconductor device. The main difference between the devices is the construction of the gate structure, where the traditional metal electrode is replaced by a special polymer membrane sensitive to concentration of ions in an electrolyte flowing over the gate. The numerical simulations presented in this paper, concern the problem of the ion mixture composition estimation based on noisy sensor measurements. The estimation is performed knowing the membrane selectivity coefficients. Additionally, the estimation accuracy is improved employing the function specification algorithm, dedicated for solving various inverse problems. The algorithm can be easily implemented as a digital filter.